The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Electronic Fuel Injection is the primary method of fuel distribution in compression-ignition and spark-ignition internal combustion engines. A fuel injector is a solenoid-actuated or piezo-electric valve device mounted on an engine and positioned to deliver pressurized fuel to a combustion chamber of an engine cylinder. Each injector is preferably energized each combustion cycle for a period of time, or pulsewidth, determined based upon pre-calibrated parameters for engine operating conditions. Multiple fuel injection events can occur each combustion cycle for each cylinder, including a main fuel injection event preceded by a pilot injection event to stabilize combustion, minimize combustion noise and increase fuel efficiency.
Pilot injection fuel mass is small in relation to the mass of fuel metered out for the main fuel injection event. Pilot injection fuel mass can be difficult for the fuel injection system to deliver in terms of precision and consistency. Injecting a fuel mass that is too small fails to initiate a pilot injection event, resulting in a missed pilot combustion event. A missed pilot injection event can lead to increased combustion noise and deterioration of emissions performance. To prevent a missed pilot injection event, engine control systems can be calibrated offline. This approach can lead to a pilot injection fuel mass that is greater than a minimum required pilot mass to induce pilot combustion.